Re: Per-cpu IDT patch

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 03/07/2020 à 07:11, s ymgch a écrit :
> Hi all,
>
> I tried to make an IDT per-cpu. The patch is here:
> http://www.netbsd.org/~yamaguchi/pcpu-idt.patch
>
> The summary of modifications is as follows.
> - Add an IDT pointer and idt_allocmap into struct cpu_info
> - Change prototype of cpu_init_idt()
>     - void => struct cpu_info*
>     - for loading an IDT address in struct cpu_info*
> - Copy a part of IDT entries from cpu 0 at attaching a CPU
>     - for the same entries, for example, exceptions, db, etc.
>
> This function can be enabled by PCPU_IDT option that is newly provided.

Why would we want a per-cpu IDT? To increase the number of entries?

> Does this patch look good?
> Please let me know if you have any comments about this.

Since the idt page is moved into pcpu_entry, it can be removed from
pcpu_area

Maxime